Download Lecture 1: Introduction, evolution, climate constraints

Ecology
[BIO 2483a]
Dr. Gabor Sass
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Dr. Gabor Sass
• Office: B&G 2070 (through the
construction zone!)
• Email: [email protected]
• More about me later!!
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Office hours:
• Monday 12:00 – 12:30
• Wednesday 12:00 - 12:30
• By appointment: please email me
([email protected])
or arrange during lectures
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Classes:
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Monday and Wednesday 9:30 - 12:00
Will have 10-15 minute break
Aim to be done by 11:45
Attendance will be taken (part of
participation mark)
• No lecture on August 4 (Civic Holiday)
• All together 11 lectures!!
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Tutorials:
• Thursday 9:30 - 12:00
• Purpose: broaden ecological perspectives by:
– listening to ecologists describe their research,
– watching documentaries,
– preparing for exams
• Attendance taken (part of participation mark)
• All together 5 tutorials
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Exams:
• Mid-term: 30% (Lectures 1-5)
– July 24, 2008 - Thursday 9:30-12:00, 3M 3250
• Final: 55% (inclusive of all lectures and tutorials)
– Date: TBA [Aug. 18 - Aug. 20]
• Exams composed of:
– Multiple choice / Fill in the blanks
– Short answers
– Long answers
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Participation:
• 15% of over-all mark
– 4% attendance
– 11% = 3 mini-assignments
• [Photograph of organism] with summary (3%)
– Picture of organism, preferably from your own experience [trips,
animals, plants you see every day and interest you…]
– Paragraph describing organism and its relations to its environment
• [Ecology in the news] with summary (3%)
– Article, link to article if possible, article summarized in 1 paragraph [no
more than 200 words]
• [Letter-to-the-editor] (5%)
– Letter that is critical (or supportive) of recent news item with relevance
to topics covered in this course [150-300 words, no more!]
• Due at the beginning of tutorials 2, 4, and lecture 10
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Who is Gabor Sass?
• Hydro-ecologist:
– this sub-discipline of ecology looks at
the influence of water (hydrology) on the
abundance and distributions of species
– My research looks at hydrological
controls on algal biomass in lakes of the
boreal forest
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Who is Gabor Sass?
• B.Sc.: Environmental Science, York U.
• M.Sc.: Geography (Vegetation patterns in urban
areas), University of Toronto
• Ph.D.: Geography (Hydro-ecology of boreal
lakes), University of Western Ontario
• Currently: Post-doctoral fellow at Western in
Biology (Hydro-ecological effects of forest
harvesting)
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Who is BIO2483a?
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Outline of course
Adaptation and Evolution
Physical environment (climate, terrestrial, aquatic,
energetics, biogeochemical cycles)
Organisms and their environment (plant, animal)
Populations
(properties, growth, intraspecific regulation
Species interactions (predation, parasitism)
Communities of populations
Biodiversity
Human ecology: Population growth, climate change
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What is ecology?
The study of the interaction of living things
with:
– Each other
– Physical environment
From Greek
– “oikos” - the family household
– “logy” - the study of
– Same root as economics - management of
the household
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DEFINITIONS OF ECOLOGY
• The scientific study of the relationship
between organisms and their
environments
• From Ernest Haeckel (1866)
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Ecology Definition
“Ecology is the scientific discipline that is
concerned with the relationships between
organisms and their past, present, and
future environments.”
Source: Ecological Society of America
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Ecology tries to answer the following three
questions:
• Where are organisms found?
• How many occur there?
• Why?
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What is “the environment”?
It includes abiotic factors (e.g. climate) as
well as biotic factors (individuals of the
same and other species).
More precisely, the interaction between
abiotic and biotic factors happens within
the context of an ecosystem.
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What is an organism/what is life?
7 Life characteristics
– Organization
– Acquire materials and energy
– Homeostasis
– Growth
– Respond to stimuli
– Reproduce
– Adapt
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Levels of Organization
• Ecologist study
organisms ranging
from the various
levels of
organization:
– Individual
– Population
– Community
– Ecosystem
– Landscape
– Region
– Biosphere
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© 2008 McGraw-Hill Ryerson Ltd.
© 2008 McGraw-Hill Ryerson Ltd.
Ecology is interdisciplinary
New areas of ecology
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Conservation ecology
Restoration ecology
Global ecology
Landscape ecology
Human ecology
Ecological engineering
Ecological economics
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Ecology courses @ Western
Chemical
Animal
Community
Population
Wildlife
Conservation
Behavioral
Ecosystem
(3475 Chemical ecology)
(3435 Animal ecology)
(3445 Community ecology)
(3440 Ecology of populations)
(3446 Wildlife ecology)
(3442 Conservation biology)
(4436 Behavioral ecology)
(4405 Ecosystem ecology) 23
SPATIAL SCALES IN ECOLOGY
Can be very large, e.g.:
• How do changes in ocean currents affect
fisheries?
• How will climate change affect distribution of
vegetation zones?
Can be very small, e.g.:
• How do different parasites within a single host cell
interact?
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TIME SCALES IN ECOLOGY
Can be very long, e.g.:
• How have North American vegetation zones
changed since the end of the last glaciation over
10,000 years ago?
Can be very short, e.g.:
• How quickly do bacteria re-colonize the human
gut after an antibiotic has been taken?
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Can we study ecology without
considering role of humans?
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ECOLOGY IS A SCIENCE
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What is science?
Continual process of refining or
rejecting hypotheses
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Hypothesis
• An educated guess
• A statement of cause and effect that can be tested
• Example: plant productivity is a linear function of soil
nitrogen content
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Testing hypotheses
• Design experiment
(key is to avoid confounding factors)
• Conduct experiment
• Analyze data
• Draw conclusion, accept or reject
hypothesis
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Testing hypotheses
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Field experiment: subplots within fields received different amounts of nitrogen
Testing hypotheses
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Testing hypotheses
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Testing hypotheses
• We accept the hypothesis:
– plant productivity is a linear function of soil nitrogen
content
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TYPES OF ECOLOGICAL
STUDIES
1.
2.
3.
4.
Field observations
Field experiments / manipulations
Lab experiments
Mathematical models
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ADAPTATION AND EVOLUTION
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Adaptation and evolution
•Darwin’s voyage on HMS Beagle
•The Theory of Natural Selection
•Modes of selection
•Heritability
•Species and speciation
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Charles Robert Darwin (1809-1882)
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Voyage of the Beagle, 1831-1836
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Blue-back grassquit
Finch found in mainland Equador
Finches of the Galapagos archipelago
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Fossils of extinct animals found in the grasslands of Argentina (such as the
Glyptodont), somewhat resemble, but are not identical to, living species (such as
the armadillo)
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(a.k.a.
placental
mammals)
Native to Australia
Found
throughout
other parts
of the world
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The Theory of Natural Selection:
Nature “selects” individuals that, by good luck, happen to be born with the
best-adapted traits for their environment (better camouflage, better
speed, etc.). Such individuals survive and reproduce; the rest do not.
Over many generations the species changes, becoming better and better
adapted to its environment.
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Natural selection
Differential success (survival+reproduction)
of individuals within a population resulting
from their interactions with its environment
(individuals fit for current environment will
survive and reproduce,
THE REST WILL NOT)
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Natural selection in action:
Beak size in the medium ground
finch, Geospiza fortis
Daphne major, the Galapagos island on which the
Grants studied the medium ground finch
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EXAMPLE
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1977
Less rain due to
La Nina
< seeds
Fewer small
ones
Marked selection
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Evolution in front of
eyes: over a few
decades!!!
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Types of selection
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Types of selection
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Types of selection
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Black-bellied seedcracker
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Heritability
• Genes are the units of inheritance
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Heritability
• Genes passed from one generation to
another through reproduction:
– Sexual (genes recombining)
– Asexual (genes identical)
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Heritability
• Genotype (sum of genes in individual)
• Gene pool (sum of genes across
population)
• Phenotype (what’s expressed of
phenotype)
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Heritability
• Mutations (inheritable changes in a gene)
– Major source of genetic variation
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Heritability: example
Pea plant (Pisum sativum)
Dominant
recessive
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What constitutes a different
species?
• Morphological (physical structure)
• Biological (reproduction)
– Biological species concept: A species is a
group of individuals that could potentially
breed together in nature to produce fertile
offspring
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Reproductive isolation
• Pre-zygotic mechanisms
– Habitat selection, temporal isolation,
behaviour, structural incompatibility
• Post-zygotic mechnisms
– Reduce fitness of offspring of different
species
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Prezygotic isolation mechanisms
Geographical isolation
Red-shafted and yellow-shafted flickers
(see text)
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Prezygotic isolation mechanisms
Habitat isolation
Grassland
Forest
Will interbreed in captivity
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Prezygotic isolation mechanisms
Chorus frogs
Share same habitat but use different mating sites
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Prezygotic isolation mechanisms
Temporal isolation
Western spotted skunk
Spilogale gracilis
Eastern spotted skunk
S. putorius
Breeds in late summer
Breeds in late winter
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Prezygotic isolation mechanisms
Behavioural isolation
Eastern meadowlark
Sturnella magna
Western meadowlark
S. neglecta
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Different mating songs
Postzygotic isolation
mechanisms
Reduced hybrid viability
Leopard frogs, Rana spp.
Hybrids die before reaching maturity
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Postzygotic isolation mechanisms
Reduced hybrid fertility
Horse
Donkey
Mule (hybrid)
Healthy but sterile
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Postzygotic isolation mechanisms
Hybrid breakdown
F2 hybrids of different strains of rice are small and infertile
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Types of speciation
Speciation can take place with or
without geographic separation
• Speciation can occur in two ways:
– Allopatric speciation
– Sympatric speciation
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Sympatric (“Same Country”)
Speciation
• In sympatric speciation, speciation takes
place in geographically overlapping
populations
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Black-bellied seedcrackers:
Sympatric speciation in progress?
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Allopatric speciation
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Allopatric speciation
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Allopatric speciation
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Allopatric speciation in the salamander Ensatina escholtzii
Originated in Oregon and migrated south
Still able to interbreed
Do not interbreed
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Ostrich
(Africa)
Emu
(Australia)
Rhea
(South America)
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Human footprints
•Domestication of animals, plants
•Bio – engineering
The Physical
Environment:
Climate
Outline:
• solar radiation and latitude
• seasonality
• atmosphere and the greenhouse effect
• temperature patterns
• wind and rainfall patterns
• climographs
Readings: Ch. 3
Climate = long-term average pattern of
weather at a locality
– Local, regional or global
– Temperature, water, light, wind
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Climograph
Note distribution
of biomes is
determined
mainly by
patterns of
temperature and
rainfall
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Solar radiation drives this Earth
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Photosynthetically active radiation (PAR)
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SHORT
LONG
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Effect of latitude
Sunlight hitting the earth near the poles is spread out over a larger surface area than
that hitting the equator. As a result, mean temperatures tend to decrease with
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increasing latitude.
Seasonal variations in sunlight and temperature
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Latitudinal trends in temperature are altered by elevational
effects and the effects of continental/marine environments
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Imaginary non-rotating Earth
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Ocean currents
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Precipitation
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Convective precipitation
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Dry climates occur near 30o latitude
and near the poles. Tropical and
temperate regions tend to
experience more rainfall.
Moist air ascending
Dry air descending
Dry air descending
Moist air ascending
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Intertropical convergence zone
Where the NE trade winds meets the SW trade winds
Produces the rainy/dry seasons
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Orographic precipitation
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Effect of mountains: orographic precipitation
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Climate variability
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•Urban-heat island
•Pollution related fog
•Global climate change
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Mean global
temperatures have
fluctuated over the last
400,000 years
Changes in the abundance
of spruce pollen (left) and
oak pollen (below) in
sediments ranging in age
from 500 years to 21,500
years. Spruce trees have
moved north since the
melting of the Laurentide ice
sheet, while oaks have
expanded their range
northwards and westwards.
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Distribution of tropical forest at present (left) and during the last ice age (at right)
in South America. Fragmentation of the forest during the ice age resulted in
many “islands” of forest with high speciation rates. These areas are biodiversity
hotspots today.
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For next lecture:
• Please read Chapters 4 and 5
• Start looking for pictures / articles …
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